Discovery date : 1817
Discovered by: Jöns Jacob Berzelius
Origin of the name: The name is derived from 'selene', the Greek name for the Moon.
Allotropes : Red Se, Grey Se, Black Se
~>SELENIUM is a portable software-testing framework for web applications. Selenium provides a playback tool for authoring tests without the need to learn a test scripting language.
| FACT BOX | |||
| Group | 16 | Melting point | 220.8°C, 429.4°F, 494 K |
| Period | 4 | Boiling point | 685°C, 1265°F, 958 K |
| Block | d | Density (g cm−3) | 4.809 |
| Atomic number | 34 | Relative atomic mass | 78.971 |
| State at 20°C | Solid | Key isotopes | 80Se |
| Electron configuration | [Ar] 3d104s24p4 | CAS number | 7782-49-2 |
| ChemSpider ID | 4885617 | ChemSpider is a free chemical structure database | |
Selenium was discovered by Jöns Jacob Berzelius at Stockholm in 1817. He had shares in a sulfuric acid works and he was intrigued by a red-brown sediment which collected at the bottom of the chambers in which the acid was made.
At first he thought it was the element tellurium because it gave off a strong smell of radishes when heated, but he eventually realised that it was in fact a new element. He also noted that it was like sulfur and indeed had properties intermediate between sulfur and tellurium. Berzelius found that selenium was present in samples of tellurium and gave that element its characteristic smell. He also became affected by it personally – it can be absorbed through the skin – and it caused him to experience the bad breath associated with those who work with this element.